Cleaning compositions for removing etching residue and method of using

ABSTRACT

An etching residue remover for cleaning etching residue from a substrate, derived from a mixture of at least hydroxylamine, an alkanolamine which is miscible with said hydroxylamine, water, and, optionally, a chelating agent, wherein the hydroxylamine and the alkanolamine are present in amounts sufficient to clean etching residue from the substrate.

RELATED PATENT APPLICATIONS

This application is a continuation of application Ser. No. 08/790,229,filed Jan. 28, 1997, which is a divisional of Ser. No. 08/523,889, filedSep. 6, 1995, now U.S. Pat. No. 5,672,577, which is a continuation ofSer. No. 08/273,143, filed Jul. 14, 1994, now U.S. Pat. No. 5,482,566,which is a divisional of Ser. No. 07/911,102, filed Jul. 9, 1992, nowU.S. Pat. No. 5,334,332, which is a continuation-in-part of Ser. No.07/610,044 filed Nov. 5, 1990, now U.S. Pat. No. 5,279,771 entitled"Stripping Compositions Comprising Hydroxylamine and Alkanolamine,"having the same inventor as the present invention.

FIELD OF THE INVENTION

The present invention is directed to a stripping and cleaningcomposition comprising hydroxylamine and at least one alkanolamine forremoving resists and etching residue from a substrate. One or more polarsolvents can additionally be included in the composition when used as astripper. No solvents are utilized when the composition is used as acleaner. The cleaning composition preferably also includes a chelatingagent. The stripping composition is especially suitable for removing aphotoresist from a substrate during the manufacture of semiconductorintegrated circuits and the removal of cured polymer coatings from asubstrate, such as a polyimide coating, without damaging the substrate.The cleaning composition is useful for removing etching residue when aresist is removed from the substrate utilizing a composition or methodother than the composition as disclosed in U.S. Ser. No. 07/610,044 andherein.

BACKGROUND OF THE INVENTION

During the fabrication of microcircuits, the precise positioning of anumber of appropriately doped regions on a slice of semiconductor isrequired followed by the positioning of one or more interconnectionpatterns on the semiconductor. Positive-type resists have beenextensively used as masking materials to delineate patterns onto asubstrate so that the patterns can be subsequently etched or otherwisedefined into the substrate. The final step in preparing the substratethen involves removing the unexposed resist material from the substrate.Increasingly, however, plasma etching, reactive ion etching or ionmilling is used to define the pattern in a substrate which renders theresist mask substantially impossible to remove by stripping agentscontaining one or more of the following solvents: halogenatedhydrocarbons such as, for example, methylene chloride ortetrachloroethylene; amines and their derivatives such as, for example,dimethylformamide, dimethyl-acetamide, pyrrolidone, diethanolamine, andtriethanolamine; glycol ethers, such as, for example, ethylene glycolmono-ethyl ether, 2-butoxyethanol, and 2-(butoxyethoxy)ethanol; andalkylsulfone, such as, for example, dimethylsulfone.

Additionally, during such etching processing, an organometallicby-product compound is formed as a sidewall polymeric material. Theabove-mentioned solvents are also ineffective in removing this sidewallorganometallic polymer. A recently developed technique effective forphotoresist removal is plasma oxidation, also known as plasma ashing.However, while this process is effective for removing a photoresist, itis not effective for removing the sidewall organometallic polymer formedduring the etching process.

Further, polyimides are increasingly used in microelectronics asfabrication aids, passivants, and inter-level insulators. The use of apolyimide as a fabrication aid includes application of the polyimide asa photoresist, planarization layer in a multi-level photoresist schemeand as an ion implant mask. In these applications, the polymer isapplied to a wafer or substrate, subsequently cured or patterned by asuitable method and removed after use. Many conventional strippers arenot sufficiently effective in removing the polyimide layer once thepolyimide has been subjected to a severe curing operation. The removalof such polyimides is normally accomplished by boiling the substrate inhydrazine or in an oxygen plasma.

Accordingly, a composition suitable for stripping a resist so as toremove the resist and the sidewall organometallic polymer would providesubstantial advantages over conventional strippers.

Further, in the event a composition which is incapable of removing boththe resist and the formed by-products is not utilized, such asconventional plasma oxidation, a composition which is capable ofremoving such etching residue is required and advantageous. If etchingresidue is not removed from the substrate, the residue can interferewith subsequent processes involving the substrate.

The demand for new wafer cleaning technology for use after etching andresist removal in particular increases as the industry enters intosubmicron processing techniques. The requirement for a cleaning solutionto remove all types of residue generated as a result of plasma etchingof various types of metals, such as aluminum, aluminum/silicon/copper,titanium, titanium nitride, titanium/tungsten, tungsten, silicon oxide,polysilicon crystal, etc., presents a need for more effective chemistryin the processing area.

More specifically, during the fabrication of microcircuits, thesubstrate surface can be aluminum, titanium, silicon oxide orpolysilicon and patterns are delineated thereon by chemical etching.Increasingly, plasma etching, reactive ion etching or ion milling areused, and such etching processes produce undesirable by-products fromthe interaction of the plasma gases, reacted species and thephotoresist. The composition of such by-products is generally made up ofthe etched substrates, underlying substrate, photoresist and etchinggases. The formation of such by-products is influenced by the type ofetching equipment, process conditions and substrates utilized. Theseby-products are generally referred to as "sidewall polymer," "veil" or"fences" and cannot be removed completely by either oxygen plasma orconventional solvents, such as N-methyl-2-pyrrolidone,diethyleneglycolbutyl-ether, dimethylacetamide or the like, which areconventionally used to remove resists. Examples of alkaline/solventmixture types of photoresist strippers which are known for use instripping applications include dimethylacetamide or dimethylformamideand alkanolamines as described in U.S. Pat. Nos. 4,770,713 and4,403,029; 2-pyrrolidone, dialkylsulfone and alkanolamines as describedin U.S. Pat. Nos. 4,428,871, 4,401,747, and 4,395,479; and 2-pyrrolidoneand tetramethylammonium hydroxide as described in U.S. Pat. No.4,744,834. Such stripping compositions, however, have only provensuccessful in cleaning "sidewall polymer" from the contact openings andmetal line etching in simple microcircuit manufacturing involving asingle layer of metal process when the metal structure involves mainlyAl--Si or Al--Si--Cu and the "sidewall polymer" residue contains only anorganometallic compound with aluminum. The cleaning mechanism involvingsuch materials has been studied by EKC Technology, Inc. and Intel Corp.,as presented at the K.T.I. Conference in 1989 in the presentationentitled "Metal Corrosion in Wet Resist Stripping Process," by P. L.Pai, C. H. Ting, W. M. Lee and R. Kuroda. Due to the corrosive nature ofsuch strippers as described above, the "sidewall polymer" is removedeither by attacking the organoaluminum compound or the metal surfaceitself and causing the "sidewall polymer" residue to be lifted off.Further, in addition to the use of the stripping composition, mechanicalscrubbing, such as ultrasonic vibration, is required to achieve completeremoval of the "sidewall polymer."

The most current submicron processing techniques utilized in theindustry involves multi-levels of metal and multi-level interconnectingprocesses. Such processes usually incorporate metal materials includingTiN, TiW, Ti, TiSi, W, WSi and the like. The use of such materialsresults in the generation of new organometallic material by-productsduring plasma etching, whether formed intentionally or unintentionally,which renders the cleaning incomplete when utilizing existingcommercially available stripping and cleaning products. Such findingswere described at the SPIE Symposium on Microlithography in 1991 in apresentation entitled "Plasma Etching and Reactive Ion Etching" by JohnW. Coburn. In particular, it has been found that the residue remainingon the substrate surface after removal of a resist by plasma ashing haschanged from the organometallic to the corresponding oxide, such asTiO₂, which is chemically inert to mild alkaline strippers. The effectof such poor cleaning results in low device yield, low devicereliability, and low device performance.

Therefore, conventional solvents used as stripping compositions areineffective in removing sidewall organometallic and metal oxide residuewhich is present following use of the current technology to removeresists. Even plasma ashing, which has been found effective for removingphotoresists, is not effective for removing the sidewall organometallicpolymer formed during etching processes.

OBJECTS OF THE INVENTION

Accordingly, a primary object of the present invention is to provide astripping and cleaning composition comprising hydroxylamine and at leastone alkanolamine for removing a resist and etching residue from asubstrate and a method of using the composition.

A further primary object of the present invention is to provide astripping and cleaning composition for removing organometallic and metaloxide residue from a substrate, in particular residue formed duringetching and resist removal processes involving the substrate, withoutadversely damaging the substrate surface or hindering subsequentoperation or process steps involving the substrate.

A further primary object of the present invention is to provide acleaning composition including hydroxylamine, at least one alkanolamine,at least one chelating agent, and water for removing organometallic andmetal oxide residue from a substrate and a method of using thecomposition.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is directed to a stripping and cleaningcomposition containing hydroxylamine and at least one alkanolamine whichis miscible with the hydroxylamine. Further, when utilized as astripping composition, the composition can optionally contain one ormore polar solvents. The addition of a polar solvent strengthens theeffectiveness of the stripping composition. The stripping compositionsallow for the clean removal of a resist from a substrate.

The stripping compositions of the present invention are particularlysuitable for removing a photoresist material from a substrate, inparticular, during the manufacture of a semiconductor integrated circuitwithout adversely affecting or hindering subsequent manufacturingoperation or process steps.

Further, the stripping compositions of the present invention aresuitable for removing cured polymer resists from a substrate, such as apartially or fully cured polyimide coating, and for removingorganometallic polymers formed on a substrate during plasma etchingprocesses.

When a stripping composition other than as described above is utilizedto remove a resist, however, polymeric and other by-products resultingfrom the etching processes are not removed. Accordingly, furthercleaning of the substrate is required. In addition to the abovedescribed stripping and cleaning composition, the present invention isalso directed to providing a cleaning composition includinghydroxylamine, at least one alkanolamine which is miscible with thehydroxylamine, at least one chelating agent, and water. The addition ofa chelating agent increases the stability and effectiveness of thecleaning composition, in particular, by making the composition capableof removing etching residue from substrates which contain metal elementsother than aluminum such as titanium (Ti), tungsten (W), silicon (Si)and silicon oxide (SiO). The cleaning compositions of the inventionallow for the clean removal of organometallic and metal oxide etchingresidue from a substrate surface following removal of the resisttherefrom. The most preferred chelating agents are 1,2-dihydroxybenzeneand derivatives thereof according to the formula ##STR1## where R₁ andR₂ can be either H, t-butyl, OH, COOH or the like.

The cleaning compositions of the present invention are particularlysuitable for removing organometallic and metal oxide residues from asubstrate, in particular, during the fabrication of a submicron (i.e.,less than 0.8 microns) integrated circuit without adversely affecting orhindering subsequent manufacturing operation or process steps involvingthe substrate. Further, the cleaning compositions of the invention arealso effective in removing organometallic residue outgasing which hasbeen deposited on parts of the etching equipment utilized in theprocessing. Such equipment can be made of polycarbonate, ceramic oraluminum.

The method of removing a resist or etching residue from a substrateusing the compositions of the present invention involves contacting asubstrate containing the resist or etching residue with the compositionat a temperature and for a time sufficient to remove the particularresist or etching residue present.

DESCRIPTION OF THE DRAWING

FIG. 1 shows etched wafer residue following the use of plasma ashing toremove a resist from a silicon oxide dielectric layer which had beenearlier plasma etched.

FIG. 2 shows the results of an analysis using ion mass spectrometry(LIMA) of the residue shown in FIG. 1. Such analysis indicates that theresidue contains metal oxide and trace amounts of organic material.

FIGS. 3A and 3B show the results of a comparison test utilizing acleaning composition of the present invention (FIG. 3A) and a strippingcomposition as described in U.S. Pat. No. 4,403,029 (FIG. 3B) inrelation to a silicon oxide dielectric layer containing etching residuethereon which is present following removal of a resist by plasma ashing.By comparing FIG. 3A with FIG. 3B, it can be seen that all theorganometallic residue was removed using the composition of the presentinvention while residue remained following use of the strippingcomposition described in U.S. Pat. No. 4,403,029.

FIGS. 4A and 4B show the results of a comparison test utilizing acleaning composition of the present invention (FIG. 4A) and a strippingcomposition as described in U.S. Pat. No. 4,770,713 (FIG. 4B) inrelation to a silicon dielectric layer which contained etching residuefollowing removal of a resist therefrom by plasma ashing. As evidentupon a comparison of FIG. 4A with FIG. 4B, the composition of thepresent invention removed all the organometallic residue while the othercomposition did not.

FIG. 5A shows a microcircuit pattern of polysilicon over silicon oxidecontaining etching residue which remained on the substrate followingplasma etching. FIG. 5B shows the same microcircuit pattern followingcleaning with a composition of the present invention. As evident from acomparison of FIG. 5A with FIG. 5B, it can be seen that the residue hasbeen removed.

FIG. 6A shows residue which remained on a metal substrate after theremoval of a photoresist from the substrate by plasma ashing. FIG. 6Bshows the same substrate following cleaning with a composition of thepresent invention.

FIGS. 7A-7D show the results of comparison tests using a cleaningcomposition of the present invention (FIGS. 7A and 7B) and aN-methyl-2-pyrrolidone solvent/alkanolamine base stripper (FIGS. 7C and7D) in relation to openings on a silicon oxide dielectric layer. Asshown in FIGS. 7A and 7B, all the organometallic residue was removedusing the composition of the present invention while, as evident fromFIGS. 7C and 7D, residue remained on the substrate treated with thestripper.

FIG. 8A shows residue remaining on a wafer following etching and theremoval of a photoresist therefrom. FIG. 8B shows the same waferfollowing cleaning with a composition of the present invention. All theresidue on the wafer was removed.

FIG. 9 illustrates the results of Example 15 below wherein the stabilityof cleaning Compositions L, N and R were compared.

DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT

The stripping composition of the present invention containshydroxylamine, at least one alkanolamine, and, optionally, at least onepolar solvent. The stripping compositions exhibit synergistic strippingproperties suitable for removing resists, such as photoresists includingthose which have been treated in a plasma etching environment and curedpolymer resists such as polyimide coatings. Additionally, the strippingcompositions provide cleaning of the substrate by removingorganometallic polymers formed on a substrate during plasma etchingprocesses.

The stripping composition preferably contains at least about 5% byweight of hydroxylamine and at least about 10% by weight of at least onealkanolamine. Optionally, the stripping composition can also containfrom about 5%-85% by weight of at least one polar solvent.

When a stripping composition as described above is not utilized toremove a resist from a substrate, organometallic polymer and metal oxideby-products formed in the etching and resist removal are not removed.Further, depending on the extent of the residue build-up, etchingresidue may remain when a non-aluminum based substrate is utilized.Accordingly, additional cleaning of the substrate is required. Thepresent invention also provides a cleaning composition includinghydroxylamine, at least one alkanolamine, at least one chelatingcompound, and water. The cleaning compositions of the present inventionare free of organic solvents. The cleaning compositions are suitable forremoving organometallic and metal oxide residue formed on a substrate,in particular residue formed during plasma etching processes. Thesubstrate can include aluminum and non-aluminum metal elements such astitanium, tungsten, silicon and silicon oxide. The extent and type ofresidue remaining is determined by the etching equipment utilized,process conditions and substrates utilized.

The cleaning composition preferably includes from about 5% to 50% byweight of hydroxylamine, from about 10% to 80% by weight of at least onealkanolamine, from about 5%-30% by weight of at least one chelatingagent, with the remaining balance of the composition being made up ofwater, preferably high purity deionized water.

The mechanism of the present invention for providing effective cleaningis believed to be on the basis that the organometallic compounds andmetal oxides are reduced by the hydroxylamine and become more soluble inthe water and alkanolamine solution. The presence of the chelatingagents or ligands allows the metal ions to form soluble complexes insolution and not precipitate out from solution. The organometalliccompound is represented as --(--O--M^(+n) --C--)-- and the mechanism canbe represented as follows:

    NH.sub.2 OH+--O--M.sup.+n C→M.sup.n-1 +M.sup.n-2 ##STR2##

The hydroxylamine suitable for use in the present invention has themolecular structure NH₂ OH. Hydroxylamine has properties which, in manyways, lie between those of amononia, H₂ N--H, and water, H--OH, as itsformula H₂ N--OH might suggest. Hydroxylamine can also serve as a ligandfor complexes as represented below. ##STR3##

The alkanolamines suitable for use in the present invention are misciblewith the hydroxylamine and are preferably water-soluble. Additionally,the alkanolamines useful in the present invention preferably haverelatively high boiling points, such as for example 100° C. or above,and a high flash point, such as for example 45° C. or above. Suitablealkanolamines are primary, secondary or tertiary amines and arepreferably monoamines, diamines or triamines, and, most preferably,monoamines. The alkanol group of the amines preferably has from 1 to 5carbon atoms.

Preferred alkanolamines suitable for use in the present invention can berepresented by the chemical formula R₈ R₉ --N--CH₂ CH₂ --O--R₁₀ whereinR₈ and R₉ can be H, CH₃, CH₃ CH₂ or CH₂ CH₂ OH and R₁₀ is CH₂ CH₂ OH.

Examples of suitable alkanolamines include mono-ethanolamine,diethanolamine, triethanolamine, tertiary-butyldiethanolamineisopropanolamine, 2-amino-1-propanol, 3-amino-1-propanol,isobutanolamine, 2-amino-2-ethoxyethanol, and 2-amino-2-ethoxy-propanol.

Polar solvents suitable for use in the stripping composition of thepresent invention include ethylene glycol, ethylene glycol alkyl ether,diethylene glycol alkyl ether, triethylene glycol alkyl ether, propyleneglycol, propylene glycol alkyl ether, dipropylene glycol alkyl ether,tripropylene glycol alkyl ether, N-substituted pyrrolidone,ethylenediamine, and ethylenetriamine. Additional polar solvents asknown in the art can also be used in the composition of the presentinvention.

Preferred chelating agents suitable for use in the cleaning compositionof the present invention include 1,2-dihydroxybenzene and derivativesthereof according to the formula ##STR4## wherein R₁ and R₂ can beeither H, t-butyl, OH, COOH or the like.

Additional chelating agents as known in the art may also be used in thecomposition of the present invention. For example, chelating agentswhich are metal ion free chelating agents may be utilized, such asthiophenol and its derivative according to the formula ##STR5## where R₁=OH or COOH; or ethylene diamine tetracarboxylic acid, of the formula##STR6## where R₁, R₂, R₃ and R₄ can be either H or NH₄, and itsammonium salt. Sodium, potassium or the like salts would not thereforebe suitable for use based upon the understood mechanism of ioniccontamination in a microcircuit as caused by cleaning and set forthabove. As evident from the above formula, the carboxylic acid may bemono-, di- or tri-substituted rather than tetra-substituted.

A preferred cleaning composition of the present invention includes 30%by weight hydroxylamine, 25% by weight 2-amino-2-ethoxyethanol, 5% byweight 1,2-dihydroxybenzene and 50% by weight of water.

The stripping compositions of the present composition are effective inremoving a wide range of positive photoresists but are particularlyuseful in removing photoresists commonly consisting of anortho-naphthoquinone diazide sulfonic acid ester or amide sensitizerwith novolak-type binders or resins. Examples of commercially availablephotoresist compositions which the stripping compositions of the presentinvention effectively remove from a substrate include K.T.I.photoresists 820, 825; Philip A. Hunt Chemical Corp. Waycoat HPR 104,HPR 106, HPR 204 and HPR 206 photoresists; Shipley Company, Inc.photoresists of the AZ-1300 series, AZ-1400 series and AZ-2400 series;and Tokyo Ohka Kogyo Co., Ltd. photoresist OFPR-800.

Further, the stripping compositions of the present invention areeffective in removing polyimide coatings from substrates even when thepolyimide coatings have been subjected to a high temperature cure,including a cure performed at a temperature as high as about 400° C.Examples of commercially available polyimide compositions which thestripping compositions of the present invention effectively remove froma substrate includes Ciba Geigy Proimide 293, ASAHI G-6246-S, a negativeimageable polyamide, and DuPont PI2545 and PI2555.

Examples of substrates from which the stripping and cleaningcompositions of the present invention remove photoresists withoutattacking the substrates themselves include metal substrates such asaluminum, titanium/tungsten, aluminum/silicon, aluminum/silicon/copper;and substrates such as silicon oxide, silicon nitride, andgallium/arsenide; and plastic substrates such as polycarbonate.

The cleaning compositions of the present invention are also effective inremoving organometallic and metal oxide residue generated on thesubstrate of the etching equipment utilized. Examples of commerciallyavailable etching equipment include Lam Research, Tegal, Electrotech,Applied Material, Tokyo Electron, Hitachi and the like.

The method of removing a resist or other material from a substrate usingthe stripping compositions of the present invention involves contactinga substrate having a resist thereon with a stripping composition of thepresent invention for a time and at a temperature sufficient to removethe resist. The time and temperature are determined based on theparticular material being removed from a substrate. Generally, thetemperature is in the range of from about 50° C. to 150° C. and thecontact time is from about 2 to 30 minutes.

The method of cleaning a substrate using the cleaning compositions ofthe present invention involves contacting a substrate havingorganometallic and metal oxide residue thereon with a cleaningcomposition of the present invention for a time and at a temperaturesufficient to remove the residue. The substrate is generally immersed inthe cleaning composition. The time and temperature are determined basedon the particular material being removed from a substrate. Generally,the temperature is in the range of from about ambient or roomtemperature to 100° C. and the contact time is from about 2 to 60minutes.

Examples illustrating the removal of a resist from a substrate undervarying conditions using the stripping compositions of the presentinvention are described further below. Thereafter, examples illustratingthe removal of etching residue from a substrate are set forth. Thefollowing examples are provided to further illustrate the presentinvention and are not intended to limit the scope of the presentinvention.

Examples of stripping compositions according to the present inventionsuitable for removing a resist from a substrate are set forth in Table Ibelow.

                                      TABLE I                                     __________________________________________________________________________    Stripping                                                                           Hydroxylamine                                                                        Alkanolamine   Solvent                                             Composition Wt. % Wt. % Wt. %                                               __________________________________________________________________________    A     10%    90% 2-Ethoxy-2-Amino Ethanol                                                                 0%                                                  B 50% 50% 2-Ethoxy-2-Amino Ethanol 0%                                         C 10% 45% 2-Ethoxy-2-Amino Ethanol 45% N-Methyl-2-Pyrrolidone                 D 10% 45% Diethanolamine 45% N-Methyl-2-Pyrrolidone                           E 50% 50% Diethanolamine 0%                                                   F 20% 30% Diethanolamine 50% Dipropyleneglycol Ethyl Ether                    G 35% 35% Diethanolamine 30% Diethyleneglycol Butyl Ether                     H 35% 50% 2-Ethoxy-2-Amino Ethanol 15% Triethyleneglycol Butyl Ether                                     I 25% 25% Tertiary Butyldiethanolamine 50%                                   N-Methyl-2-Pyrrolidone                              J 50% 25% 2-Ethoxy-2-Amino Ethanol 25% Diethylenetriamine                     K 25% 50% 2-Ethoxy-2-Amino Ethanol 25% Diethylenetriamine                   __________________________________________________________________________

EXAMPLE 1

Example 1 illustrates the removal of a photoresist from a substrateusing different stripping compositions of the present invention. Thesubstrate is treated in a conventional manner prior to the treatment ofthe substrate with the stripping compositions of the present invention.

More specifically, wafer substrates were spun in a commerciallyavailable spinning apparatus with the photoresist K.T.I. 820 at spinningspeeds ranging from 1000 to 5000 RPM resulting in the formation of filmshaving a thickness of about 0.5-2.5 microns on the substrate. After thuscoating the substrate, the substrate was heated for about 10-20 minutesat 80° C.-90° C. to drive out any traces of solvent from thephotoresist. Next, the photoresist was selectively exposed using animage pattern transfer technique as known in the art. The exposed areasof the positive photoresist were solubilized in a developer solution.After such development, the pattern on the wafer was cleaned using aspray rinse and the wafer hard-baked. Baking temperatures can be in therange of from about 125° C.-200° C. Baking causes the resist to hardenand adhere firmly to the surface of the substrate. The final step in thewafer preparation process is the removal of the unexposed positivephotoresist material. Removal of this material is performed usingstripping compositions of the present invention. Stripping baths wereprepared and maintained at a constant temperature in 1000 ml beakers.The hard-baked coated wafers were immersed in the stripping compositioncontained in the beakers. The contents of the beakers were subjected tointermittent agitation for specified times. After the wafer was removedfrom the stripping bath, the wafer was rinsed in a cascade of deionizedwater and spun dry in a spin/rinser dryer. The effectiveness of thestripping operation was judged by the time required for removal of thecoating layer and the amount of photoresist residue remaining on thewafer surface following rinsing. Specific examples performed asdescribed above utilizing stripping compositions as set forth in Table Iare set forth in Table II below.

                  TABLE II                                                        ______________________________________                                                                   Bath                                                 Resist Hard Stripping Bath Time                                               Bake Temp. Composition Temp. (Mins) Observations                            ______________________________________                                        125° C.                                                                         A         65° C.                                                                         10    Resist dissolved in 3                              minutes; Rinsed very                                                          cleanly                                                                   150° C. A 65° C.  5 Resist lifted very                              cleanly from substrate                                                    180° C. B 65° C. 10 Resist dissolved in 2                           minutes; Rinsed clean                                                     150° C. D 75° C.  5 Resist dissolved in 3                           minutes; Rinsed clean                                                   ______________________________________                                    

EXAMPLE 2

Example 2 illustrates the removal of a polyimide resist coating from asubstrate using stripping compositions of the present invention. As inExample 1, a conventional coating method was utilized.

More specifically, wafer substrates were coated with ASAHI G-6246-Snegative imageable polyimide to a thickness of 16 microns. The coatedwafers were baked at 250° C. to remove the solvent present in thepolyimide. The polyimide coating was then exposed in a Nikon Stepperwith a 350 mJ dose and developed in the Asahi A-145/C-210 developer. Thewafers were then immersed in a bath containing a stripping compositionand processed in the stripping bath as described in Example 1 accordingto the temperatures and times as set forth in Table III below.

                  TABLE III                                                       ______________________________________                                                           Bath                                                         Stripping Bath Time                                                           Composition Temp. (Min) Observations                                        ______________________________________                                        B          70° C.                                                                         10        Polyimide. dissolved;                                 Rinsed cleanly                                                             C 65° C. 10 Polyimide dissolved;                                          Rinsed cleanly                                                             E 75° C. 10 Polyimide dissolved                                           after 2 minutes; Rinsed                                                       very cleanly                                                               I 65° C. 10 Polyimide dissolved;                                          Rinsed very cleanly                                                      ______________________________________                                    

EXAMPLE 3

Example 3 illustrates the removal of a polyimide coating from asubstrate having multiple layers of materials thereon.

A coating of Ciba Geigy Proimide 293 was spun onto a 3" Gallium/Arsenidewafer to a thickness of 4 microns. The polyimide coating was fully curedat 400° C. for 30 minutes. Silicon oxide was then deposited to athickness of 1000 Angstrom on the polyimide coated surface. Thereafter,a positive photoresist was applied over the silox surface and a patterncreated in the photoresist through the steps of exposure and resistdevelopment. The image created was then transferred from the photoresistto the silox surface by etching the silicon oxide using a plasma etchingtechnique as known in the art. The pattern was further transferred tothe polyimide layer by etching the photoresist and polyimidesimultaneously. This procedure resulted in a pattern which covered allthe regions on which no metal film was desired. Thereafter, atitanium/tungsten metal film was deposited over the substrate-polyimidecombination. Thus, the metal film contacted the substrate only in thoseregions where the metal film was required. Finally, the polyimide wasremoved from the substrate by immersing the treated wafer in a strippingcomposition of the present invention. The metal film as present in thesubstrate was not attacked by the stripping composition and thepolyimide dissolved and rinsed clearly away from the substrate.

EXAMPLE 4

Example 4 illustrates the degree of metal corrosion present to a metalfilm when the stripping compositions of the present invention contactsuch metal film coated substrate for varying time periods.

Aluminum was sputtered onto silicon wafers to a thickness of 6000Angstroms. The sheet resistance of the metal film on the wafers wasmeasured using a Prometrix VP-10 four point probe prior to treating thewafer with a stripping composition. The wafers were then immersed instripping composition B or stripping composition C as described in TableI for 10, 15, and 20 minutes. Thereafter, the sheet resistance of themetal film was again measured. The amount of metal corrosion was basedon the percentage of change in thickness present with respect to themetal film. The results are set forth in Tables IV and V below.

                  TABLE IV                                                        ______________________________________                                        STRIPPING COMPOSITION B                                                           Time                                                                        (Min) Rs Initial Rs Final Change In thickness                               ______________________________________                                        20     47.74        48.39   1.34%                                               15 47.86 48.33 0.97%                                                          10 47.71 47.85 0.29%                                                           0 38.39 38.39 0.00%                                                        ______________________________________                                    

                  TABLE V                                                         ______________________________________                                        STRIPPING COMPOSITION C                                                           Time                                                                        (Min) Rs Initial Rs Final Change In thickness                               ______________________________________                                        20     47.05        47.39   0.72%                                               15 47.17 47.46 0.61%                                                          10 47.2   47.3  0.21%                                                          0 47.47 47.47 0.00%                                                        ______________________________________                                    

Varying examples illustrating the removal of etching residue from asubstrate under varying conditions using the cleaning compositions ofthe present invention are set forth below.

Examples of cleaning compositions according to the present inventionsuitable for removing etching residue from a substrate are set forth inTable VI below.

                  TABLE VI                                                        ______________________________________                                        Cleaning  Hydroxylamine                                                                              Alkanolamine                                             Composition Wt. % Wt. %                                                     ______________________________________                                          L 25% 50% 2-Amino-2-Ethoxy Ethanol                                            M 20% 60% 2-Amino-2-Ethoxy Ethanol                                            N 20% 55% 2-Amino-2-Ethoxy Ethanol                                            O 17.5% 50% Monoethanolamine                                                  P 8.75% 30% 2-Amino-2-Ethoxy Ethanol                                          Q 15% 60% Monoethanolamine                                                    R 15% 70% 2-Amino-2-Ethoxy Ethanol                                          Cleaning  Water        1,2-dihydroxybenzene                                     Composition Wt. % Wt. %                                                     ______________________________________                                          L 25% 0%                                                                      M 20% 0%                                                                      N 20% 5%                                                                      O 17.5% 15%                                                                   P 63.5% 2.5%                                                                  Q 20% 5%                                                                      R 15% 0%                                                                    ______________________________________                                    

EXAMPLE 5

Example 5 illustrates the problem of residue remaining on a wafersubstrate following plasma etching and ashing. FIG. 1 shows etched waferresidue present on an etched substrate following plasma ashing.Specifically, silicon oxide used as a dielectric layer has a patternetched for a multi-layer interconnect according to a standard plasmaetching process. A photoresist which was used as a masking material hasalready been removed by oxygen plasma ashing. Analysis of the residuepresent on the etched wafer was analyzed by ion mass spectrometry(LIMA). The results of the analysis are as shown in FIG. 2. The analysisconfirms that the residue contains metal oxide and trace amounts oforganic material.

EXAMPLE 6

Example 6 illustrates the effect of the cleaning composition of thepresent invention on a wafer as determined by C/V testing. C/V shiftmeasurement is a means utilized to determine the effect of a chemicalused to clean a wafer. A high voltage shift is mainly caused by mobileion contamination to the wafer. Such contamination will adversely affectsubsequent process steps and may eventually cause failure of themicrocircuits.

The test evaluation compares the C/V shift of different conventionalphotoresist stripping compositions to the cleaning composition of thepresent invention. All wafers used were known to be good silicon oxidesubstrates. All chemicals were heated on a hot plate to themanufacturers' suggested operating temperature using a pyrex beaker.Each of the beakers utilized was new and had not been previously used inany chemical processing. Individual beakers were used for each product.After immersing the silicon oxide wafer in the described composition,the wafers were rinsed and dried. Table VII sets forth the operatingconditions and the results of the C/V shift test.

                                      TABLE VII                                   __________________________________________________________________________    Composition            Process                                                  Product Manufacturer U.S. Pat. Conditions Results                           __________________________________________________________________________    PRS-3000   J. T. Baker                                                                          4,403,029                                                                          90° C./20 min.                                                                 +15.624 volts                                    EMT 300 EMT 4,770,713 90° C./20 min. +2.440 volts                      N-Methyl-2-Pyrrolidone J. T. Baker 4,395,479 90° C./20 min.                                         +2.044 volts                                     Nophenol 944 EKC 4,395,384 100° C./20 min.  -0.368 volts                                             Composition N -- -- 65° C./20 min.                                    +0.221 volts                                     Control -- -- -- -0.576 volts                                               __________________________________________________________________________

A negative reading means no change in C/V shift. The cleaningComposition N according to the present invention as described above wasshown to provide a cleaner surface than any of the positive photoresiststrippers tested.

EXAMPLE 7

Example 7 illustrates the results of a comparison test betweenComposition Q of the present invention as described above and thestripping composition described in U.S. Pat. No. 4,403,029 and soldunder the name PRS-2000 by J. T. Baker. The results of the comparisontest are shown with respect to an opening having the size of 1.2 micronin FIGS. 3A and 3B. Each opening was present on a silicon oxidedielectric layer which was etched using a standard silicon oxide plasmaetching process. The photoresist was removed from the layer followingetching by oxygen plasma ashing. The substrate was then processed byimmersing the substrate in Composition Q as described above for 10minutes at 65° C. A micrograph from a scanning microscope as shown inFIG. 3A indicates that Composition Q removed all the organometallicresidue. As shown in FIG. 3B, residue remained on the substrate when anetched wafer prepared under the same process conditions was processed byimmersion in PRS-2000 for 10 minutes at 65° C.

EXAMPLE 8

Example 8 illustrates the results of a comparison test betweenComposition N as described above and a stripping composition asdescribed in U.S. Pat. No. 4,770,713 and sold under the name ACT-150I.ACT-150I is a dimethylacetamide solvent based photoresist stripper.

The comparison test results are shown in FIGS. 4A AND 4B with respect toopenings having a size of 1.0 micron. Each opening was present on asilicon oxide dielectric layer which was etched using a standard siliconoxide plasma etching process. The photoresist was removed by oxygenplasma ashing. The substrate was then processed by immersion inComposition N as described above for 30 minutes at 45° C. A micrographfrom a scanning electron microscope as shown in FIG. 4A shows thatComposition N completely removed all the organometallic residue withoutdamaging the silicon oxide substrate. FIG. 4B shows a substrate preparedunder the same process conditions after immersion in ACT-150I for 30minutes at 45° C. As shown in FIG. 4B, the stripping composition onlypartially removed the etching residue.

EXAMPLE 9

Example 9 illustrates the cleaning of polysilicon etching residue. Amicrocircuit pattern of polysilicon over silicon oxide was etched inplasma etching equipment using HBr as an etching gas. The photoresistwas removed by oxygen plasma ashing. The etching residue, which ismostly Si--C--Br, is shown in FIG. 5A to remain on the polysiliconcircuit line following the removal of the photoresist. When the waferwas further processed by immersion in Composition N of the presentinvention at 65° C. for 20 minutes, all of the etching residue wasremoved from the substrate as shown in FIG. 5B.

EXAMPLE 10

Example 10 illustrates the cleaning of a metal etch residue from asubstrate. A sandwich metal substrate of TiW/Al--Si--Cu/TiW waspatterned and etched in a plasma metal etcher, i.e., Applied Material8330 Metal Etcher. Such metal etcher is a batch etching equipment andtherefore is capable of treating more than one wafer at a time. Due tothe manner of etching performed by such etching equipment, a lesseramount of "polymer" residue is built-up during etching. Since a lowerdegree of polymer residue is present, a cleaning composition without achelating agent is sufficient to remove the etching residue. As shown inFIG. 6A, residue remained on the metal line after the photoresist wasremoved by oxygen plasma ashing. The wafer was then processed byimmersion in Composition M as described above at 65° C. for 30 minutes.As shown in FIG. 6B, Composition M served to remove all theorganometallic residue from the surface.

EXAMPLE 11

Example 11 illustrates the cleaning of a submicron circuit by means ofvia opening having a size of 0.6 microns on a silicon oxide dielectriclayer which had been etched using a standard silicon oxide plasmaetching processing. In particular, an oxide etcher as sold by LamResearch was utilized. In this process, the etching residue is mostlysilicon containing polymer with a small ratio of metal in thecomposition. Accordingly, a cleaning composition of the invention notcontaining a chelating agent is capable of removing the residue. Theunderlying layer was a metal substrate of TiN/Al--Si--Cu. Thephotoresist masking material was removed by oxygen plasma ashing. Thesubstrate was then processed by immersion in Composition L as describedabove for 30 minutes at 60° C. A cross-section micrograph from ascanning microscope as shown in FIG. 7A indicates that Composition Lremoved all the organometallic residue. As shown in FIG. 7B, however,residue remained inside the opening when an etched wafer processed inthe same conditions was treated in N-methyl-2-pyrrolidonesolvent/alkanolamine based stripper for 60 minutes at 90° C. in anultrasonic bath.

EXAMPLE 12

Portions of silicon oxide etching equipment which are made of heavygauge aluminum were removed from the etching equipment for cleaning. Theconventional procedure utilized to remove the deposited outgas residueon the etching equipment is by sandblasting. Sandblasting, however, is atime consuming procedure. It has been found that the residue depositedon the aluminum portion of the etching equipment can be easily removedby immersion in a composition of the present invention. An aluminumportion of etching equipment was immersed in Composition P for 30minutes at 40° C. Following rinsing and drying, it was observed that theresidue was removed.

EXAMPLE 13

The conventional process of cleaning a ceramic ring which forms a partof metal etching equipment involves either sandblasting or scrubbing byhand. Composition L was utilized to clean such ceramic ring by immersingthe ceramic ring in an ultrasonic bath for 45 minutes at 35° C. It wasfound that the deposits on the ceramic ring were completely removed.

EXAMPLE 14

Example 14 illustrates the cleaning of metal etch residue. AnAl--Si--Cu/CW/TiW metal pattern sitting on a plasma enhanced TEOS wasutilized. The wafer had 50% overetching. P-5000 as sold by AppliedMaterial was used for the metal etching. The P-5000 is a single waferetcher and due to the processing technique of the etching equipment, ahigher build-up of polymer remains following the etching which is moredifficult to remove than that described in Examples 10 and 11 above. Asandwich metal substrate of Al--Si--Cu/W/TiW was patterned and etched inthe plasma metal etcher P-5000. The small amount of residue left on thecorner of the metal line after the photoresist was removed by oxygenplasma ashing and was cleaned using Composition M at 65° C. for 30minutes. Such cleaned substrate is shown in FIG. 8A. Composition M didnot provide for complete removal of the residue. A similar etched waferwas then processed by immersion in Composition O as described above at65° C. for 30 minutes. As shown in FIG. 8B, Composition O removed allthe organometallic residue from the surface. Composition M does notcontain a chelating agent and Composition O contains a chelating agent.

EXAMPLE 15

Example 15 illustrates that cleaning solutions containing chelatingagents have increased stability as compared to the cleaning solutionsnot containing such chelating agents. Compositions L, N and R, asdescribed above, were each placed in separate sealed Pyrex flasks andmaintained at room temperature for a period of 80 days. A sample wastaken from each flask at regular intervals and analyzed to determine itsactivity. The activity of the cleaning compositions is measured by thereduction potential of the hydroxylamine. It can be seen from FIG. 9that Compositions R and L lost their activity much faster thanComposition N.

As will be apparent to one skilled in the art, various modifications canbe made within the scope of the aforesaid description. Suchmodifications being within the ability of one skilled in the art form apart of the present invention and are embraced by the appended claims.

I claim:
 1. An etching residue remover for cleaning etching residue froma substrate, derived from a mixture consisting essentially ofhydroxylamine, an alkanolamine which is miscible with saidhydroxylamine, and water, wherein the hydroxylamine and the alkanolamineare present in amounts sufficient to clean etching residue from thesubstrate.
 2. The etching residue remover according to claim 1, whereinthe hydroxylamine is present in an amount of from about 5-50% by weight.3. The etching residue remover according to claim 1, wherein saidalkanolamine is present in an amount of from about 10-80% by weight. 4.The etching residue remover according to claim 1, wherein the alkanolgroup of said alkanolamine contains from 1 to 5 carbon atoms.
 5. Theetching residue remover according to claim 1, wherein said alkanolamineis selected from the group consisting essentially of monoamines,diamines, and triamines.
 6. The etching residue remover according toclaim 1, wherein said alkanolamine has a formula R₈ R₉ --N--CH₂ CH₂--O--CH₂ CH₂ OH wherein R₈ and R₉ can be H, CH₃, CH₃ CH₂, or CH₂ CH₂ OH.7. An etching residue remover for removing etching residue from asubstrate, derived from a combination comprising:hydroxylamine; analkanolamine which is miscible with said hydroxylamine; a compoundselected from the group consisting of compounds of formula I: ##STR7##wherein R₁ and R₂ can be either H, t-butyl, OH, or COOH, and compoundsof formula II: ##STR8## where R₃ is OH or COOH; and water, wherein thehydroxylamine and the alkanolamine are present in amounts sufficient toclean etching residue from the substrate.
 8. The etching residue removeraccording to claim 7, wherein the hydroxylamine is present in an amountof from about 5-50% by weight.
 9. The etching residue remover accordingto claim 7, wherein said alkanolamine is present in an amount of fromabout 10-80% by weight.
 10. The etching residue remover according toclaim 7, wherein said compound is present in an effective amount of upto about 30% by weight.
 11. The etching residue remover according toclaim 7, wherein the alkanol group of said alkanolamine contains from 1to 5 carbon atoms.
 12. The etching residue remover according to claim 7,wherein said alkanolamine is selected from the group consistingessentially of monoamines, diamines, and triamines.
 13. The etchingresidue remover according to claim 7, wherein said alkanolamine has aformula R₈ R₉ --N--CH₂ CH₂ --O--CH₂ CH₂ OH wherein R₈ and R₉ can be H,CH₃, CH₃ CH₂, or CH₂ CH₂ OH.
 14. An etching residue remover for cleaningetching residue from a substrate, derived from a mixture comprisinghydroxylamine, an alkanolamine which is miscible with saidhydroxylamine, and water, wherein the hydroxylamine and the alkanolamineare present in amounts sufficient to clean etching residue from thesubstrate, wherein said alkanolamine has a formula R₈ R₉ --N--CH₂ CH₂--O--CH₂ CH₂ OH wherein R₈ and R₉ can be H, CH₃, CH₃ CH₂, or CH₂ CH₂ OH.15. The etching residue remover according to claim 14, furthercomprising a compound selected from the group consisting of compounds offormula I: ##STR9## wherein R₁ and R₂ can be either H, t-butyl, OH, orCOOH, compounds of formula II: ##STR10## where R₃ is OH or COOH, andethylene diamine tetracarboxylic acids of formula III: ##STR11## whereR₄, R₅, R₆ and R₇ can be either H or NH₄, or an ammonium salt thereof.16. The etching residue remover according to claim 14, wherein thehydroxylamine is present in an amount of from about 5-50% by weight. 17.The etching residue remover according to claim 14, wherein saidalkanolamine is present in an amount of from about 10-80% by weight.